Case-hardening apparatus.



A. W. MAOHLBT.

CASE HARDBNING APPARATUS.

APPLICATION FILED MAY 25, 1906.

Patented J an. 2, 1912.

R 1 W A IJ Q. Q? .N w m a My v +M f,

UNITED STATES PATENT OFFICE.

ADOLPH w. macnnEg-or ELIZABETH, new JERSEY.

I casn-na meume Ann -terns. 1,013,191., Specificationot Letters-Patent."Patented Jan. 2,1912.

Application filed May 25, Serial 1T0. 318,679. I

To all whom it ma concern} V Be it known that I, AnoLPH W. MacHLE'r, acitizen of the United States, residing in Elizabeth, in the county ofUnion andState of New Jersey, have invented certain new and usefulImprovements in Case-Hardening Apparatus, of which the following is aspecification. I w

This invention relates principally to. case.- hardening steel or ironarticles.

In my co-pending application No. 244,244 Patent No. 822,460'is set fortha manner of case-hardening by inclosing articles in. aretort, andboth'heating and rotating theretort while a current of carburizing gascirculates therethrough; and my ctypending application No- 292,515filedDecember 19, 1905, is disclosed a'manner of thinning thecarburizing gas by. means of ammonia.

One of the objects of the present invention is to simplify and reducethe cost of the heating apparatus and the operation there'- of, "as Wellas to adapt the same for certain kinds of work, and another object istoprovide for securing the proper quality of carburizing gas, as well asfor diluting the same, .whereby the user may operate inde pendently ofthe ordinary illuminating gas supply, which is not always available, andwhich in some cases-is not suitable for car,- burizing.

According to the first part of the present invention, the articles areplaced directly in the flame chamber of a retort which is in the form ofan oven, and heated directly by the flames, and then the flames areextinguished, and the oven is filled with carburiz ing gas, whichcements the articles by means of their own retained heat. The walls ofthe oven are greatly thickened for the purpose of retaining heat, thusdelaying the cooling of the articles sufficiently to enable them to besubstantially cemented by their retained heat, or by the heat retainedin the oven.

The top of the oven is provided with one or more capacious vents for theescape of products of combustion durlng the heating of the articles, andthese vents are providedwith closures, whereby they may be closed duringthe subsequent carburizing- 0per a. tion; and thG'OVBIl is also providedwith, a

constricted regulatable vent for controlling ing the vcarburizingoperation.

carburilzing' gas therethrough. The carburizing gas is preferablyintroduced .into the oven through the same pipe which feeds theburners.I r V I In practicing my invention in one Way,

.ammonla gas may be led, from a tank through a body of naphtha, theammonia taking up a quantity of naphtha, and being then led into'theretort'or oven to carburize the articles; the ammonia serving as adi1uent for the carburizing gas whichit derives from the naphtha, andavoiding the deposit of free carbon upon'the articles, and hasten Bythis means, the user becomesindependent "of the supply of illuminatingor heating gas from the usual sources, ,whichis liable tofluctuate inquality,'or which may not be available, and is assured a continuoussupply of carburizing gasof uniform quality.

Other objects, features and advantages will hereinafter appear. j

'In the accompanying drawings, Figure 1 shows one form of apparatusoperating in accordance with my'present invention portionsof the ovenand "the, oil tank being broken away to disclose the construction. Fig.2 is a) cross-section of the oven, showing the burnerslet into theopposite walls thereof. i

The oven comprises side walls 1, 2, rear walls 3, top 4, front wall 5and base 6, all made of refractory material andv greatly thickened inproportion to the capacity of the oven, so that they retain heat,thereby to delay the cooling of the articles, and

hence prolong the cementing operation until a substantial shell isformed upon the arti-.

cles. The oven is preferably containedin an iron boxing7, and rests uponan iron base 8 supported uponlegs 9. At the front of the oven isprovided a door or lid 10 of thick refractory material, which maybelifted by means of books 11. In thetopof the oven are provided capaciousvents 12, which are made open during the generation of flames in theoven and may be closed by conical plugs 12' during the subsequentfilling of the oven with carburiz'ing gas.

Gas or other fuel is supplied tothe oven through a pipe 13 controlled bya valve 14; and air is supplied through a pipe 15 conthe renewal.through. the pipe 13 of freshhence enabled to control the condition andtrolled by a valve 16; the air being preter-' ably supplied underpressure. The mixed air and fuel are distributed by means of pipes 17,18, 19 and 20, to burners 21 in the base of the oven. Preferably theburners are arranged'in two series in the opposite walls 1, 2, so as todirect the flames along the floor 6 of the oven. A thick plate 22 ofeither iron or refractory material may lie horizontally just above theburners, spaces being left at 23 around the edges of the screen for thepassage of flames up into the body of the oven, whereby the flames arecaused to heat the walls of the oven very hot, as well as articlescontained therein. The screen also because ofits great thlckness servesas a reservoir of heat efl'ective'to prolong the carburizing operation.

In operation the door 10 s lifted and the articles 24-, such as tubes,or bars or devices of any shape are placed upon the screen or table 22.Before the door 10 is dropped, the valves 14 and 16 are opened and themixture of the gas and fuel is ignited at the burners 21, the productsof combustion escaping through the vent or vents 12. The heatingproceeds until the articles reach a carburizin'g heat which is say abovered heat and below the melting point; at which time the door and thewalls of the oven, as well as the'screen 22, are heated to about thesame temperature as the articles, and serve as reservoirs of heat toprolong the carburizing operation. Thereupon the valve '16 is closed toout off the air and extinguish the flames at the burners, and the vents1-2 are closed by the lugs 12; and gas may continue to flow -1n throughthe pipe'13 to immediately fill the oven and carburize the articles;this gas being of any suitable quality, as coal gas or any othercarburizing fluid. Preferably a constricted vent pipe 46 is fitted inthe lower part of the door 10 or one of the walls of the oven, so thatthe current of carburizing gas may pass slowly through the oven, thusinsuring the drawing off of the vitiated gas, and

gas. This vent may be regulated by a valve 47. The gas escaping throughthis vent and igniting in the air shows its condition by the color ofits flame. The operator is flow of the gaseous atmosphere in the oven byregulating either valve 47 or 14 or both. Owing to the thickness of theheated walls, the cooling'of the metal articles is greatly delayed, andthey are enabled to become cemented to a substantial depth by means oftheir own retained heat, or by means of the heat retained in the oven.After the articles cool to a certain extent, the chemical action of thegas thereon, ceases; and- In case the cementation does not proceed to asuflicient depth, they may be allowed to remain in the oven, and thevalve 16 may be opened to admit air, and the oven again heated as beforeby raising the arti-- cles to the carburizing point, whereupon theflames may be again extinguished and carburizing gas supplied to theoven, thus causing the cementation of the articles to proceed to agreater depth; and this operation may be repeated on the same articlesuntil they have the required depth of cementation.

Ammonia or other inert gas may if desired be admitted through a pipe 48which joins the pipe 17, and is provided with a valve 49, the latterbeing closed during the operation of heating the oven. The mixture ofgas and ammonia may be controlled ity suitable for case-hardening, or ifno gas is available from ordinary sources, for the purpose ofcarburizing, the devices now to be described may be employed. A tank 50is nearly filled with naphtha 51. A tank 52 containing ammonia or othersuitable lnert gas under pressure, is put in connect1on with the tank 50by means of a pipe 53, the flow of ammonia being controlled by a valve54 in said pipe. The latter extends down into the oil tank. 50, andterminates near the bottom thereof in a spray -55. Bubbles of ammoniaare seen at 56 rising from the spray, and during this action. they takeup a plenum of naphtha or carbon fill ng the top of the tank 50 with gascomprlslng ammonia and carbon. This gas may be led through the pipe 48from the top of the tank 50 through the pipes 17 18 and 19, and into theoven through the burners 21;- the valves 14 and 16 being closed and theflames'extinguished. Pref-- .erably the proportion of ammonia whichVariations may be resorted to within the scope of the invention, andportions of the improvements may be used without others. Having thusdescribed my inventi0n, I claim:

1. In combination, a close-d oven having walls of refractory material, aseries of burners opening within said oven; the latter provided with acapacious vent for products of combustion, and with means for closingsaid vent, and means for supplying to said burners either carburizinggas alone or mixed air and fuel at will constricted means being providedfor slowly'venting carburizing gas from the oven; said walls beingsufficiently thick in proportion to the capacity of the oven, tomaintain iron or steel articles there in at carburi'zing heat for asubstantial length of time after the extinction of flames at theburners, to enable cementation of the articles to proceed to asubstantial depth before they cool.

2. In combination, a closed oven having greatly thickened walls ofrefractory material and provided with a capacious vent for products ofcombustion and with means for closing said vent,'a series of burners insaid oven, means for permitting extinction of flames at the burners, andmeans for supplying'mixed air and fuel to said burners and for supplyingthe oven with carburizing gas after extinction of flames at the burners,regulatable means being provided for slowly venting the carburizing gasfrom the oven.

A case-hardening apparatus. comprising a closed oven having walls ofrefractory material which are greatly thickened in pro-portion .to thecapacity .of the oven, :1

series of burners insaid oven, means for permitting extinction of flamesat-vtheburners, means for supplying mixed air and fuel to sald burners,and means for supply ng and passing a current of mixed ammonia andcarburizing gas through the oven after extinction of the flames at theburners; said oven having a capacious' vent for products of combustion,and a closure for said vent.

4. The combination with a closed oven whose walls are formed of rfractory Inatcrial, of burners for mixed air and fuel in said oven, andmeans for filling the oven, after extinction of the flames at theburners,

with a different gas capable of chemically acting upon the articlescontained in the oven while they remain heated; the walls of the ovenbeing greatly thickened so as to retain suflicient heat to maintain thearticles in the oven at the required heat during such chemical action;said oven provided with a vent for the products of combustion and aclosure for said vent.

5. The combination of a closed oven having walls thickened to retainheat, a series of burners for mixed air and fuel opening into said ovenat the base t-hereof, a thick heat-retaining bed slab between saidburners and the body of the oven, flame passages being left between theedges of the bed and the walls of the oven, and means for supplyingcarburizing gasto said oven after extinction of flames at said burnersthe oven being provided with a capacious vent for the products ofcombustion and'with a closure for said vent, and also having aregulatable constricted vent for the carburizing gas.

6. The combination of an oil tank connected with an oil supply andhaving automatic means to regulate the flow of oil into the tank, anammonia tank, a pipe leading froni the ammonia tank and terminating in aspray in the lower portion of the oil tank. means for controlling theflow of ammonia into the oil tank, and a case-hardening retort providedwith heating means and a vent and in communication with the upper part.of said oil tank.

7. The combination with a: retort in the form of a closed oven havingthickened heatretaining Walls, of a series of burners opening into saidoven, means for supplying mixed air and fuel to said burners. and meansfor applying and introducing cal-bib rizing fluid thinned with ammoniainto said retort through said burners; the retort being provided with acapacious vent for the products of combustion and a closure for saidvent, and also with'a constricted vent for the carburizing fluid.

. --8. The combination of a closed oven having its walls thickened toretain heat and provided with 'a door, a series of burners for mixed airand fuel opening into said oven,

means for permitting extinction of flames at the burners, the latterprovided with a capacious vent for the products of combustion and with atapering solid plug to fit said vent, means being provided for supplyingcarbnrizing gas to the oven after extinction of flames at the burners,and the oven alsohaving a regnlatableconstricted vent for thecarbnrizing gas.

9. In combination, an oven having greatly thickened walls of refractorymaterial and provided with a capacious vent for products of combustionand with means for closing said vent, a series of burners in said oven,means for permitting extinction of flames at the burners, and means forsupplying mixed air and fuel to said burners and for supplying the ovenwith carburizing gas diluted with another gas after extinction of flamesat the burners.

7 10. A carburizing retort in the form of a closed oven having a doorand provided with burners and means forpermitting the extinction.of'flames at the burners, and hav-.

in at carburizing heat for a substantial length of time after theextinction of flames at the burners, to enable cementation of thearticles to proceed to a substantial depth before they cool, provisionbeing made for passing carburizing gas slowly through the heated oven.

11. A carburizing retort in the form of a closed oven having walls and adoor all of refractory material and provided in its bottom portion witha heat-bed distinct from the Walls of the oven; burners for mixing airand fuel provided in the bottom. portion of said oven; and means forpermitting the extinction'of flames at the burners; said walls and doorbeing sufficiently thick in proportion to the capacity of the oven, toserve as an ample reservoir for heat to maintain iron or steel articlestherein at carburizing heat for a substantial length of time after theextinction of flames at the burners, to enable ceinentation of'thearticles to proceed to .a substantial depth before flames, gas supplypipes 13, air supply pipe 15, and a pipe 4:8 for the supply of inertgas; said walls, heat-bed and door being sufiioiently thick. inproportion to the capacity of the oven, to maintain iron or steelarticles therein at carburizing heat for a substantiallength of timeafter the extinction of flames at the burners, to enable cementation ofthe articles to proceed to a substantial depth before they cool.

13. A earburizing retort in the form of a closed oven having walls and adoor all of refractory material and provided in the bottom portion ofits flame chamber with a heat-bed distinct from the walls of the oven;

burners for mixing air and fuel provided in the bottom portion of saidoven; means'for permitting the extinction of flames at the burners; aclosable escape for the flames from the oven, and a constrictedrgas-vent; said walls being sufficiently thick in proportion to thecapacity of the oven to form a'heat reservoir, to maintain iron or steelarticles therein at carburizing heat for a substantial length of timeafter the extinction of flames at the burners, to enable cementation ofthe articles to proceed to a substantial depth before they cool.

14:. The combination of a closed oven,

burners opening in said oven for mixed air and gas, means forextinguishing the burntory material of sufliciently great thickness toconstitute a heat reservoir capable of maintaining the containedarticles atthe necessary temperature to enable them to become carburizedto a substantial depth.

ADOLPH W. MACHLET. Vitnesses SAMUEL R. OGDEN, PI-uLIr C. OSTERMAN.

- Copies of this patent may, be obtained for five cents each, byaddressing the Commissioner of Patents,

Washington, D. G.

